This application claims the priority of German Patent Document 199 43 004.7, filed Sep. 9, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a cooling device for an internal combustion engine which in use is installed in a passenger motor vehicle. The cooling device includes at least one radiator disposed in a cooling circuit connected with an internal combustion engine by a supplying pipeline and a returning pipeline for flowing cooling water. The cooling circuit also has a heat exchanger for cooling oil of an automatic transmission.
Equipment for controlling the temperature of the transmission oil is known, for example, from European Patent Document EP 0 787 929 A2, which equipment interacts with a radiator of a liquid-cooled internal combustion engine. With this equipment, an attempt is made to keep the temperature of the transmission oil at a defined level.
The European Patent Document EP 0 785 379 A2 describes a transmission cooling system, which has a heat exchanger. This heat exchanger is integrated in an oil sump of a transmission housing which is interlocked with a liquid-cooled internal combustion engine.
It is an object of the invention to provide a cooling device for an internal combustion engine with a heat exchanger for cooling oil of a transmission, for which the heat exchanger is installed in a structurally simple manner in the cooling circuit and the transmission oil is cooled concertedly.
Pursuant to the invention, this objective is accomplished by providing a cooling device of the above-noted general type, wherein a cooling device for an internal combustion engine which in use is installed in a passenger motor vehicle comprises at least one radiator disposed in a cooling circuit and connected with an internal combustion engine by a supplying pipeline and a returning pipeline through which cooling water is flowing, which cooling circuit has a heat exchanger for cooling oil of an automatic transmission, wherein a flow resistance is connected in the supplying pipeline before the internal combustion engine, and wherein a branching pipeline leading away from the supplying pipeline is connected behind the heat exchanger with the flow resistance and is connected with the heat exchanger of the transmission.
Further advantageous features of preferred embodiments of the invention are described below and in the claims.
The main advantages achieved with the invention are seen therein that, on the one hand, the heat exchanger for cooling engine oil can be installed in a simple manner in the cooling circuit of the cooling device and, on the other hand, is acted upon concertedly. This is supported by the flow resistance. This flow resistance is a thermostat, which bypasses the cooling cycle in the warming-up phase of the internal combustion engine, a loss of pressure at the thermostat being utilized in order to produce an adequate pressure gradient for the functioning of the heat exchanger in the branch line. The shut-off valve in the branch line ensures that the temperature of the oil in the transmission, upon reaching the operating temperature of the internal combustion engine, can be varied independently of the cooling circuit between the radiator and the internal combustion engine in such a manner that the heat exchanger becomes effective only when the temperature of the transmission oil has reached a predetermined value which may be relevant for the fuel consumption of the internal combustion engine.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.